#include <IndexIVF.h>

Inheritance diagram for faiss::IndexIVF:

Public Member Functions
	IndexIVF (Index *quantizer, size_t d, size_t nlist, MetricType metric=METRIC_INNER_PRODUCT)

void	reset () override
	removes all elements from the database.

void	train (idx_t n, const float *x) override
	Trains the quantizer and calls train_residual to train sub-quantizers.

void	add (idx_t n, const float *x) override
	Quantizes x and calls add_with_key.

virtual void	train_residual (idx_t n, const float *x)

virtual void	search_preassigned (idx_t n, const float x, idx_t k, const idx_t assign, const float centroid_dis, float distances, idx_t *labels, bool store_pairs) const =0

virtual void	search (idx_t n, const float x, idx_t k, float distances, idx_t *labels) const override

long	remove_ids (const IDSelector &sel) override
	Dataset manipulation functions.

virtual void	merge_from (IndexIVF &other, idx_t add_id)

virtual void	copy_subset_to (IndexIVF &other, int subset_type, long a1, long a2) const

size_t	get_list_size (size_t list_no) const

void	make_direct_map (bool new_maintain_direct_map=true)

double	imbalance_factor () const
	1= perfectly balanced, >1: imbalanced

void	print_stats () const
	display some stats about the inverted lists

Public Member Functions inherited from faiss::Index
	Index (idx_t d=0, MetricType metric=METRIC_INNER_PRODUCT)

virtual void	add_with_ids (idx_t n, const float x, const long xids)

virtual void	range_search (idx_t n, const float x, float radius, RangeSearchResult result) const

void	assign (idx_t n, const float x, idx_t labels, idx_t k=1)

virtual void	reconstruct (idx_t key, float *recons) const

virtual void	reconstruct_n (idx_t i0, idx_t ni, float *recons) const

void	compute_residual (const float x, float residual, idx_t key) const

void	display () const

Public Attributes
size_t	nlist
	number of possible key values

size_t	nprobe
	number of probes at query time

Index *	quantizer
	quantizer that maps vectors to inverted lists

bool	quantizer_trains_alone
	just pass over the trainset to quantizer

bool	own_fields
	whether object owns the quantizer

ClusteringParameters	cp
	to override default clustering params

std::vector< std::vector< long > >	ids
	Inverted lists for indexes.

size_t	code_size
	code size per vector in bytes

std::vector< std::vector < uint8_t > >	codes

bool	maintain_direct_map
	map for direct access to the elements. Enables reconstruct().

std::vector< long >	direct_map

Public Attributes inherited from faiss::Index
int	d
	vector dimension

idx_t	ntotal
	total nb of indexed vectors

bool	verbose
	verbosity level

bool	is_trained
	set if the Index does not require training, or if training is done already

MetricType	metric_type
	type of metric this index uses for search

Additional Inherited Members
Public Types inherited from faiss::Index
typedef long	idx_t
	all indices are this type

Detailed Description

Index based on a inverted file (IVF)

In the inverted file, the quantizer (an Index instance) provides a quantization index for each vector to be added. The quantization index maps to a list (aka inverted list or posting list), where the id of the vector is then stored.

At search time, the vector to be searched is also quantized, and only the list corresponding to the quantization index is searched. This speeds up the search by making it non-exhaustive. This can be relaxed using multi-probe search: a few (nprobe) quantization indices are selected and several inverted lists are visited.

Sub-classes implement a post-filtering of the index that refines the distance estimation from the query to databse vectors.

Definition at line 45 of file IndexIVF.h.

Constructor & Destructor Documentation

faiss::IndexIVF::IndexIVF	(	Index *	quantizer,
		size_t	d,
		size_t	nlist,
		MetricType	metric = `METRIC_INNER_PRODUCT`
	)

The Inverted file takes a quantizer (an Index) on input, which implements the function mapping a vector to a list identifier. The pointer is borrowed: the quantizer should not be deleted while the IndexIVF is in use.

Definition at line 31 of file IndexIVF.cpp.

Member Function Documentation

void faiss::IndexIVF::copy_subset_to	(	IndexIVF &	other,
		int	subset_type,
		long	a1,
		long	a2
	)		const

virtual

copy a subset of the entries index to the other index

if subset_type == 0: copies ids in [a1, a2) if subset_type == 1: copies ids if id % a1 == a2 if subset_type == 2: copies inverted lists such that a1 elements are left before and a2 elements are after

Definition at line 248 of file IndexIVF.cpp.

void faiss::IndexIVF::make_direct_map ( bool new_maintain_direct_map = true )

intialize a direct map

Parameters

new_maintain_direct_map if true, create a direct map, else clear it

Definition at line 69 of file IndexIVF.cpp.

void faiss::IndexIVF::merge_from	(	IndexIVF &	other,
		idx_t	add_id
	)

virtual

moves the entries from another dataset to self. On output, other is empty. add_id is added to all moved ids (for sequential ids, this would be this->ntotal

Reimplemented in faiss::IndexIVFPQR.

Definition at line 221 of file IndexIVF.cpp.

void faiss::IndexIVF::search	(	idx_t	n,
		const float *	x,
		idx_t	k,
		float *	distances,
		idx_t *	labels
	)		const

overridevirtual

assign the vectors, then call search_preassign

Implements faiss::Index.

Reimplemented in faiss::IndexIVFPQR.

Definition at line 94 of file IndexIVF.cpp.

virtual void faiss::IndexIVF::search_preassigned	(	idx_t	n,
		const float *	x,
		idx_t	k,
		const idx_t *	assign,
		const float *	centroid_dis,
		float *	distances,
		idx_t *	labels,
		bool	store_pairs
	)		const

pure virtual

search a set of vectors, that are pre-quantized by the IVF quantizer. Fill in the corresponding heaps with the query results. search() calls this.

Parameters

n	nb of vectors to query
x	query vectors, size nx * d
assign	coarse quantization indices, size nx * nprobe
centroid_dis	distances to coarse centroids, size nx * nprobe
distance	output distances, size n * k
labels	output labels, size n * k
store_pairs	store inv list index + inv list offset instead in upper/lower 32 bit of result, instead of ids (used for reranking).

Implemented in faiss::IndexIVFPQCompact, faiss::IndexIVFFlat, faiss::IndexIVFScalarQuantizer, and faiss::IndexIVFPQ.

void faiss::IndexIVF::train_residual	(	idx_t	n,
		const float *	x
	)

virtual

Sub-classes that encode the residuals can train their encoders here does nothing by default

Reimplemented in faiss::IndexIVFPQR, faiss::IndexIVFScalarQuantizer, and faiss::IndexIVFPQ.

Definition at line 184 of file IndexIVF.cpp.

The documentation for this struct was generated from the following files:

/data/users/matthijs/github_faiss/faiss/IndexIVF.h
/data/users/matthijs/github_faiss/faiss/IndexIVF.cpp

Public Member Functions

Public Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation